Nanorod production method and nanorod produced thereby

ABSTRACT

Provided is a method of manufacturing a nanorod. The method comprising comprises the steps of: providing a growth substrate and a support substrate; epitaxially growing a nanomaterial layer onto one surface of the growth substrate; forming a sacrificial layer on one surface of the support substrate; bonding the nanomaterial layer with the sacrificial layer; separating the growth substrate from the nanomaterial layer; flattening the nanomaterial layer; forming a nanorod by etching the nanomaterial layer; and separating the nanorod by removing the sacrificial layer.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.16/077,316, filed on Aug. 10, 2018, which is a National Phase PatentApplication and claims priority to and the benefit of InternationalApplication Number PCT/KR2017/002053, filed on Feb. 24, 2017, whichclaims priority to and the benefit of Korean Patent Application No.10-2016-0024610, filed on Feb. 29, 2016, the entire content of each ofwhich is incorporated herein by reference.

TECHNICAL FIELD

The present invention relates to a method of manufacturing a nanorod anda nanorod produced thereby.

BACKGROUND ART

A nanorod is a nano-sized structure having a diameter in the range ofseveral tens of nanometers to several hundreds of nanometers and a largeaspect ratio, and a device employing the nanorod is used in variousfields such as a field effect transistor (FET), a field emission device(FED), a light emitting diode (LED), a solar cell, a gas sensor, achemical sensor, a biosensor, and the like according to applications.

A synthesis of the nanorod may be broadly divided into two methods: avapor method using a vapor-liquid-solid (VLS) mechanism employing ametal catalyst and a liquid method using a solution.

The vapor method is a method such that a state of a material is changedinto a gaseous state using high heat, and atoms in the gaseous statecondense to synthesize nanorods of various shapes. The vapor methodmakes it difficult to control sizes and properties of nanorods and touniformly arrange the synthesized nanorods.

Further, a crystal structure and an optical characteristic of a nanorod,which is produced by the liquid method, are poor due to a large numberof defects, as compared to the nanorod synthesized by the vapor method,and similar to the vapor method, there is a problem in that arrangementand formation of electrodes are difficult.

Conventional methods of producing a nanorod include chemicalpolymerization, electrochemical polymerization, chemical vapordeposition (CVD), and carbothermal reduction, but the conventionalmethods have many restrictions which require a high synthesistemperature, a reaction time, expensive vacuum equipment, the use of aharmful gas, and the like in order to obtain a high-quality nanorod.

Further, a surface crack may occur in a conventional process ofseparating a nanorod from a substrate, and damage and thermal damage maybe caused by strong heat energy and heat transfer.

DISCLOSURE Technical Problem

The present invention is directed to providing a nanorod productionmethod capable of minimizing a defective rate of a nanorod and producinga high quality nanorod, and a nanorod produced thereby.

Technical Solution

One aspect of the present invention provides a nanorod production methodincluding providing a growth substrate and a support substrate,epitaxial growing a nanomaterial layer on one surface of the growthsubstrate, forming a sacrificial layer on one surface of the supportsubstrate, bonding the nanomaterial layer to the sacrificial layer,separating the growth substrate from the nanomaterial layer, flatteningthe nanomaterial layer, etching the nanomaterial layer to form ananorod, and separating the nanorod by removing the sacrificial layer.

The growth substrate may include at least one among a glass substrate, aquartz substrate, a sapphire substrate, a plastic substrate, and abendable flexible polymer film. The growth substrate may include atleast one among gallium nitride (GaN), silicon carbide (SiC), zinc oxide(ZnO), silicon (Si), gallium phosphide (GaP), spinel (MgAl2O4),magnesium oxide (MgO), lithium aluminate (LiAlO2), lithium gallate(LiGaO2), gallium arsenide (GaAs), aluminum nitride (AlN), indiumphosphide (InP), and copper (Cu).

The support substrate may include at least one among the sapphiresubstrate, the glass substrate, a silicon carbide substrate, a siliconsubstrate, and a conductive substrate made of a metal material.

The nanomaterial layer may include at least one among ZnO, GaN, GaAs,SiC, tin oxide (SnO2), GaP, InP, zinc selenide (ZnSe), molybdenumdisulfide (MoS2), and Si.

The nanomaterial layer may be epitaxially grown by metal organicchemical vapor deposition (MOCVD).

The epitaxial growing of the nanomaterial layer on one surface of thegrowth substrate may include controlling a length of the nanorod byadjusting a deposition thickness of the nanomaterial layer.

The sacrificial layer may include an insulating layer for bonding to thenanomaterial layer and a metal layer deposited on an upper surface ofthe insulating layer to bond the insulating layer.

The sacrificial layer may be made of gold (Au), titanium (Ti), iron(Fe), silicon oxide (SiO2), or silicon nitride (SiN).

The separating of the growth substrate from the nanomaterial layer mayinclude separating the growth substrate from the nanomaterial layerusing one among a laser lift-off (LLO) method, a chemical lift-off (CLO)method, and an electrochemical lift-off (ELO) method.

The flattening of the nanomaterial layer may include flattening thenanomaterial layer separated from the growth substrate using chemicalmechanical polishing (CMP).

When the sacrificial layer is made of SiO2, the separating of thenanorod by removing the sacrificial layer may include removing thesacrificial layer using a buffered oxide etchant (BOE).

When the sacrificial layer is made of a metal layer, the separating ofthe nanorod by removing the sacrificial layer may include removing thesacrificial layer using a metal etchant.

Another aspect of the present invention provides a nanorod produced bythe above-described nanorod production method.

Advantageous Effects

A method of manufacturing a nanorod and a nanorod produced thereby,according to an exemplary embodiment of the present invention, include asacrificial layer such that a defective rate of a nanorod can beminimized by easily separating the nanorod during a process ofseparating the nanorod from a support substrate, thereby producing ahigh quality nanorod.

DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart illustrating a nanorod production method accordingto one embodiment of the present invention.

FIGS. 2A to 2G are cross-sectional views sequentially illustrating aprocess of producing a nanorod using the nanorod production methodaccording to one embodiment of the present invention.

MODES OF THE INVENTION

Hereinafter, embodiments of the present invention will be fullydescribed in detail which is suitable for easy implementation by thoseskilled in the art to which the present invention pertains withreference to the accompanying drawings. The present invention may beimplemented in various different forms, and thus it is not limited toembodiments which will be described herein. In the drawings, someportions not related to the description will be omitted and not be shownin order to clearly describe the present invention, and the samereference numerals are given to the same or similar componentsthroughout this disclosure.

In this description, the terms “comprising,” “including,” “having,” orthe like are used to specify that a feature, a number, a step, anoperation, a component, an element, or a combination thereof describedherein exists, and it should be understood that they do not preclude thepresence or addition probability of one or more other features, numbers,steps, operations, components, elements, or combinations thereof inadvance. Further, when a portion of a layer, a film, a region, a plate,or the like is referred to as being “on” another portion, this includesnot only a case in which the portion is “directly on” another portionbut also a case in which yet another portion is present between theportion and another portion. Contrarily, when a portion of a layer, afilm, a region, a plate, or the like is referred to as being “under”another portion, this includes not only a case in which the portion is“directly under” another portion but also a case in which yet anotherportion is present between the portion and another portion.

Hereinafter, a nanorod production method and a nanorod produced therebyaccording to one embodiment of the present invention will be describedin detail with reference to the drawings.

FIG. 1 is a flowchart illustrating a method of manufacturing a nanorodaccording to one embodiment of the present invention. FIGS. 2A to 2G arecross-sectional views sequentially illustrating a process of producing ananorod using the method of manufacturing a nanorod according to oneembodiment of the present invention.

Referring to FIG. 1, the method of manufacturing a nanorod may includeproviding a growth substrate and a support substrate (S10), epitaxialgrowing a nanomaterial layer on one surface of the growth substrate(S20), forming a sacrificial layer on one surface of the supportsubstrate (S30), bonding the nanomaterial layer to the sacrificial layer(S40), separating the growth substrate from the nanomaterial layer(S50), flattening the nanomaterial layer (S60), forming a nanorod byetching the nanomaterial layer (S70), and separating the nanorod byremoving the sacrificial layer (S80).

Accordingly, the method of manufacturing a nanorod according to oneembodiment of the present invention is capable of minimizing a defectiverate of a nanorod, which is caused by a process of separating a nanorod1 from a support substrate 13, and producing a high quality nanorod.

Referring to FIGS. 1 and 2A, in the providing of the growth substrateand the support substrate (S10), a growth substrate 11 is provided togrow a nanomaterial layer 15 and the support substrate 13 is provided tosupport and form sacrificial layers 17 and 19.

Meanwhile, referring to FIG. 2A, the growth substrate 11 may include atleast one among a glass substrate, a quartz substrate, a sapphiresubstrate, a plastic substrate, and a bendable flexible polymer film.Further, the growth substrate may include a transmissive substrate.

In this case, the growth substrate may include at least one amonggallium nitride (GaN), silicon carbide (SiC), zinc oxide (ZnO), silicon(Si), gallium phosphide (GaP), spinel (MgAl₂O₄), magnesium oxide (MgO),lithium aluminate (LiAlO₂), lithium gallate (LiGaO₂), gallium arsenide(GaAs), aluminum nitride (AlN), indium phosphide (InP), and copper (Cu).However, the growth substrate 11 is not limited as long as thenanomaterial layer 15 can be epitaxially grown thereon.

Meanwhile, referring to FIG. 2A, the support substrate 13 may includeone among a sapphire substrate, a glass substrate, a silicon carbidesubstrate, a silicon substrate, and a conductive substrate made of ametal material. Further, the support substrate 13 may include a circuitboard such as a printed circuit board (PCB) or a ceramic substratecontaining a ceramic.

Referring to FIGS. 1 and 2B, in the epitaxial growing of thenanomaterial layer on one surface of the growth substrate (S20), thenanomaterial layer 15 which is a material of the nanorod 1 may beepitaxially grown on one surface of the growth substrate 11.

In this case, the epitaxial growing of the nanomaterial layer on onesurface of the growth substrate (S20) may include controlling a lengthof the nanorod by adjusting a deposition thickness of the nanomateriallayer (S21).

Further, as shown in FIG. 2B, the epitaxial growing of the nanomateriallayer on one surface of the growth substrate (S20) may include epitaxialgrowing the nanomaterial layer 15 on an upper surface of the growthsubstrate 11.

At this point, the epitaxial growth refers to a growth of a crystal of asame material or a different material on the particular crystalsubstrate in a specific direction, and the epitaxial growth is referredto as epitaxy.

Further, a growth of a crystal of a same material on the substrate isreferred to as homoepitaxy or simply referred to as EPI, whereas agrowth of a crystal of a material, which is different from a material ofa substrate, on the substrate is referred to as heteroepitaxy.

Meanwhile, the nanomaterial layer 15 is a nano material constituting thenanorod 1, and the nanomaterial layer 15 may be made of one among ZnO,GaN, GaAs, SiC, tin oxide (SnO₂), GaP, zinc selenide (ZnSe), molybdenumdisulfide (MoS₂), and Si, but the present invention is not limitedthereto.

In one embodiment of the present invention, the nanomaterial layer 15may be made of any kind of nanomaterial which can be vertically grownand constitute a nanorod having a large aspect ratio.

Meanwhile, referring to FIG. 1, vapor deposition used in the epitaxialgrowing of the nanomaterial layer on one surface of the growth substrate(S20) may include at least one among atomic layer deposition (ALD),reactive sputtering, ion implantation, magnetron sputtering, laserablation, ion beam deposition, chemical vapor deposition (CVD), andplasma enhanced CVD.

However, metal organic CVD (MOCVD) may be preferably used for theepitaxial growth according to one embodiment of the present invention.That is, the nanomaterial layer 15 may be epitaxially grown using anMOCVD apparatus.

In this case, a compound having an alkyl group such as methyl or ethylmay be used as a raw material of an organometallic compound, such astrimethylgallium (Ga(CH₃)₃), trimethylaluminum (Al(CH₃)₃), and triethylphosphate ((C₂H₅O)₃PO), used in the MOCVD apparatus.

Meanwhile, the nanomaterial layer 15 is a layer for forming the nanorod1 through a subsequent process. In one embodiment of the presentinvention, in the controlling of the length of the nanorod by adjustingthe deposition thickness of the nanomaterial layer (S21), a thickness ofthe nanomaterial layer 15 corresponds to a length of the nanorod 1formed in the subsequent process so that a deposition thickness of thenanomaterial layer 15 is controlled to adjust the length of the nanorod1.

Although not shown in the drawing, a buffer layer (not shown) requiredfor the epitaxial growth may further be formed between the growthsubstrate 11 and the nanomaterial layer 15 in one embodiment of thepresent invention. At this point, the buffer layer may be formed tominimize a lattice mismatch between the growth substrate 11 and thenanomaterial layer 15.

Referring to FIGS. 1 and 2B, in the forming of the sacrificial layer onone surface of the support substrate (S30), a sacrificial layer may beformed on one surface of the support substrate 13, e.g., on an uppersurface of the support substrate 13 as shown in FIG. 2B.

At this point, in one embodiment of the present invention, thesacrificial layer may include the metal layer 19 and the insulatinglayer 17 and may be made of a metal, an oxide, or a nitride such as gold(Au), titanium (Ti), iron (Fe), silicon oxide (SiO₂), or silicon nitride(SiN), but the present invention is not limited thereto.

Further, the sacrificial layer may be deposited as a thin metal layer 19on an insulating layer to bond the nanomaterial layer 15 to theinsulating layer 17.

Alternatively, when the sacrificial layer is formed on the upper surfaceof the support substrate 13, a bonding layer (not shown) may be providedon the upper surface of the support substrate 13 to bond the supportsubstrate 13 to the sacrificial layer, but when the sacrificial layer isconfigured with a structure or a material capable of being bonded to thesupport substrate 13 without the bonding layer, the bonding layer may beomitted.

Referring to FIGS. 1 and 2C, in the bonding of the nanomaterial layer tothe sacrificial layer (S40), the nanomaterial layer 15 is bonded to theinsulating layer by bonding an upper surface of the nanomaterial layer15 to an upper surface of the metal layer 19.

The metal layer 19 and the insulating layer 17, which are thesacrificial metal layer, may be etch stop layers when the resultantnanomaterial layer is etched to form a nano node. Therefore, an etchantfor the nanomaterial layer 15 should be prevented from infiltrating intothe support substrate 13.

Meanwhile, referring to FIGS. 1 and 2D, in the separating of the growthsubstrate from the nanomaterial layer (S50), the growth substrate 11 isseparated from the nanomaterial layer 15.

At this point, a method of separating the growth substrate 11 from thenanomaterial layer 15 may include a laser lift-off (LLO) method, achemical lift-off (CLO) method, and an electrochemical lift-off (ELO)method.

The LLO method is a method of growing the nanomaterial layer 15 on thegrowth substrate 11, bonding the sacrificial layer 17 onto thenanomaterial layer, and separating the nanomaterial layer from thegrowth substrate 11 by irradiating a laser beam.

The CLO method is a method of growing the sacrificial layer on thegrowth substrate 11, growing the nanomaterial layer 15, bonding thesacrificial layer onto the nanomaterial layer 15, and separating thenanomaterial layer 15 from the growth substrate 11 using an etchant. Atthis point, the etchant selectively etches the sacrificial layer.

The ELO method grows the nanomaterial layer 15 on the growth substrate11 and forms a porous nanomaterial layer 15 through electrochemicaletching using a metal anode. Then, the ELO method regrows thenanomaterial layer 15, bonds the sacrificial layer onto the nanomateriallayer, and separates the nanomaterial layer from the growth substrate.

In the flattening of the nanomaterial layer (S60), flattening may beperformed by a chemical mechanical polishing (CMP).

Meanwhile, referring to FIGS. 1 and 2E, in the forming of the nanorod byetching the nanomaterial layer (S70), the nanomaterial layer 15 isselectively etched by the etchant with or without injecting the etchantto form the nanorod 1.

In this case, a mask material layer which is selectively etched with thenanomaterial layer 15 is formed, and the mask material layer may beformed as an insulating layer made of SiO₂ or SiN, but the presentinvention is not limited thereto.

At this point, the etchant may include sulfuric acid, phosphoric acid,potassium hydroxide, or sodium hydroxide. Meanwhile, the nanomateriallayer 15 is dry-etched in a top-down method to form the nanorod 1 whichis vertically grown.

The top-down method is a method of implementing a display in aone-to-one correspondence manner in which a single micro light emittingdiode (LED) element, which is manufactured in a top-down manner, isdisposed at a position of a sub-pixel of a large-area glass substrate.However, one end portion of the nanorod 1 is bonded to the sacrificiallayer.

Here, an etching gas used for the dry etching may include chlorine (Cl₂)or a hydrocarbon (CH₄) based gas, but the present invention is notlimited thereto. In one embodiment of the present invention, when thenanomaterial layer 15 is etched with the etchant, the sacrificial layerserves as an etch stop layer that is not etched by the etchant.

Alternatively, the etching process may be performed by dry etching orwet etching. In this case, unlike wet etching, dry etching allowsunidirectional etching, while wet etching allows isotropic etching sothat etching may be performed in any direction.

Referring to FIGS. 1 and 2F, in the separating of the nanorod byremoving the sacrificial layer (S80), the nanorod 1 is easily separatedfrom the support substrate 13 by removing the sacrificial layer bondedto one end portion of the nanorod 1.

Consequently, the nanorod production method according to one embodimentof the present invention can minimize a defective rate of the nanorodand produce a high quality nanorod.

In this case, when the sacrificial layer is made of SiO₂, which is theinsulating layer 17, the sacrificial layer may be removed using abuffered oxide etchant (BOE).

At this point, hydrofluoric acid (HF) of the etchant selectively reactswith SiO₂ or SiN to form silicon tetrafluoride (SiF₄) such that thesacrificial layer is removed.

When the sacrificial layer is the metal layer 19, the sacrificial layermay be removed using a metal etchant. At this point, a method ofremoving the sacrificial layer through etching may remove thesacrificial layer by immersing the support substrate in the BOE.

A nanorod production method and a nanorod produced thereby according toan exemplary embodiment of the present invention include a sacrificiallayer such that a defective rate of a nanorod can be minimized by easilyseparating the nanorod during a process of separating the nanorod from asupport substrate, thereby producing a high quality nanorod.

Hereinbefore, although one embodiment of the present invention has beendescribed, the spirit of the present invention is not limited to theembodiment disclosed herein, and it should be understood that numerousother embodiments can be devised by those skilled in the art that willfall within the same spirit and scope of this disclosure throughaddition, modification, deletion, supplement, and the like of acomponent, and also these other embodiments will fall within the spiritand scope of the present invention.

INDUSTRIAL APPLICABILITY

In accordance with one embodiment of the present invention, there areprovided a nanorod production method capable of minimizing a defectiverate of a nanorod and producing a high quality nanorod, and a nanorodproduced thereby.

1. A method of manufacturing a light emitting diode, the methodcomprising: forming a plurality of light emitting diodes on asacrificial layer which is disposed on one surface of a supportsubstrate; and separating the plurality of light emitting diodes fromthe support substrate by removing the sacrificial layer.
 2. The methodof manufacturing a light emitting diode of claim 1, wherein forming theplurality of light emitting diodes comprises: forming a material layeron the sacrificial layer; and etching the material layer to form theplurality of light emitting diodes.
 3. The method of manufacturing alight emitting diode of claim 2, wherein the material layer is etched ina direction perpendicular to the one surface of the support substrate toform the plurality of light emitting diodes.
 4. The method ofmanufacturing a light emitting diode of claim 2, wherein forming theplurality of light emitting diodes further comprises flattening thematerial layer after forming the material layer on the sacrificiallayer.
 5. The method of manufacturing a light emitting diode of claim 2,wherein forming the material layer on the sacrificial layer comprises:providing a growth substrate; epitaxial growing the material layer onone surface of the growth substrate; bonding the material layer to thesacrificial layer; and separating the growth substrate from the materiallayer.
 6. The method of manufacturing a light emitting diode of claim 5,wherein the growth substrate includes at least one among a glasssubstrate, a quartz substrate, a sapphire substrate, a plasticsubstrate, and a bendable flexible polymer film.
 7. The method ofmanufacturing a light emitting diode of claim 5, wherein the growthsubstrate includes at least one of gallium nitride (GaN), siliconcarbide (SiC), zinc oxide (ZnO), silicon (Si), gallium phosphide (GaP),spinel (MgAl₂O₄), magnesium oxide (MgO), lithium aluminate (LiAlO₂),lithium gallate (LiGaO₂), gallium arsenide (GaAs), aluminum nitride(AlN), indium phosphide (InP), and copper (Cu).
 8. The method ofmanufacturing a light emitting diode of claim 1, wherein the supportsubstrate includes at least one of a sapphire substrate, a glasssubstrate, a silicon carbide substrate, a silicon substrate, and aconductive substrate made of a metal material.
 9. The method ofmanufacturing a light emitting diode of claim 2, wherein the materiallayer includes at least one of zinc oxide (ZnO), gallium nitride (GaN),gallium arsenide (GaAs), silicon carbide (SiC), tin oxide (SnO₂),gallium phosphide (GaP), indium phosphide (InP), zinc selenide (ZnSe),molybdenum disulfide (MoS₂), and silicon (Si).
 10. The method ofmanufacturing a light emitting diode of claim 9, wherein the materiallayer is epitaxially grown by metal organic chemical vapor deposition(MOCVD).
 11. The method of manufacturing a light emitting diode of claim5, wherein the epitaxial growing of the material layer on one surface ofthe growth substrate includes controlling a length of the light emittingdiode by adjusting a deposition thickness of the material layer.
 12. Themethod of manufacturing a light emitting diode of claim 2, wherein thesacrificial layer is made of gold (Au), titanium (Ti), iron (Fe),silicon oxide (SiO₂), or silicon nitride (SiN).
 13. The method ofmanufacturing a light emitting diode of claim 2, wherein the sacrificiallayer includes an insulating layer on the one surface of the supportsubstrate and a metal layer on the insulating layer.
 14. The method ofmanufacturing a light emitting diode of claim 5, wherein the separatingof the growth substrate from the material layer includes separating thegrowth substrate from the material layer using one of a laser lift-off(LLO) method, a chemical lift-off (CLO) method, and an electrochemicallift-off (ELO) method.
 15. The method of manufacturing a light emittingdiode of claim 4, wherein the flattening of the material layer includesflattening the material layer separated from the growth substrate usingchemical mechanical polishing (CMP).
 16. The method of manufacturing alight emitting diode of claim 12, wherein when the sacrificial layercomprises SiO₂, the separating of the light emitting diode by removingthe sacrificial layer includes removing the sacrificial layer using abuffered oxide etchant (BOE).
 17. The method of manufacturing a lightemitting diode of claim 12, wherein when the sacrificial layer comprisesa metal layer, the separating of the light emitting diode by removingthe sacrificial layer includes removing the sacrificial layer using ametal etchant.